Identification of volatile profiles of Rio Red grapefruit at various developmental to maturity stages

Abstract

Grapefruit is an important citrus crop having unique aroma and flavour. In the current study, the juice quality parameters and volatile chemical composition of grapefruits harvested at five different periods comprising of developmental to maturity stages from June to April were studied. The headspace volatile compounds of grapefruit juice were isolated by solid phase micro-extraction (SPME) using divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fibre and identified by gas chromatography-mass spectrometry. The volatiles were separated on WAXPlus capillary column and the results were relatively quantified and expressed as perillyl alcohol equivalents. A total of 25 compounds were identified constituting to nearly 98% of the volatiles. Terpene hydrocarbons accounted for nearly 98% of total volatiles during the various harvest stages. Limonene and β-caryophyllene were found to be most abundant components in all the samples. The levels of limonene (22.3 ± 2.8–5.9 ± 1.4 mg/100 g fresh weight) decreased from June to April, whereas nootkatone was significantly higher in January (19.9 ± 4.1) and April (56.42 ± 6.31 μg/100 fresh weight) as compared to other harvests. Developmental stages and maturity had significant influence on the volatile profile of grapefruit juice.

Keywords:

• Headspace solid phase micro-extraction
• grapefruit volatiles
• maturity stages
• limonene
• nootkatone

Acknowledgements

We thank Director, Citrus Center, Texas A&M University-Kingsville, Weslaco, Texas, for providing the grapefruits during different developmental stages.